Barley is among the most ancient of the cereal crops. Barley is low in fat and is an excellent source of dietary fibre, containing beta-glucans, B-complex vitamins, vitamin E, tocopherols, and tocotrienols. Moreover, beta-glucan has been proven to reduce cholesterol and regulate blood glucose levels.
Currently, the majority of barley grown in North America is used as feed for cattle, swine, and poultry. Approximately one third of the barley supply is used for brewing malt beverages, and a very limited amount is marketed for general human consumption. Commercially available barley products include pot and pearled barley, grits, flakes, and malt flour. Cracked barley and barley flour can be incorporated into breads, and hulled barley may be used in hot breakfast cereals. However, the lengthy cooking time required (approximately one hour) has hindered wide acceptance of such products. Further, although whole grain products are currently desirable in the marketplace, the lengthy soak (several hours) required prior to cooking whole grain hulless barley has limited the marketing and use of this healthy grain.
With respect to processing of barley, traditional processing techniques include: blocking (dehulling), pearling, flaking, and milling. Blocking and pearling processes both remove the hull of the barley grain, however blocking removes part of the hull with minimum damage to the kernel, while pearling is an abrasive scouring process that gradually removes hull, bran, and germ. Pearling is usually carried out in two stages; the first stage removes only the loose hull (7 to 14% of the kernel removed) to produce pot barley. Further abrasion during the second stage of pearling removes the seed coat, aleurone, subaleurone layers, and the germ, producing a polished grain containing mainly starch, beta-glucan and protein. Pearled barley therefore includes only a fraction of the original whole grain, and excessive pearling results in a corresponding reduction in nutritional value. Pearled barley is currently used in soups, stews, salads, and as a rice extender, although the crease visible in the barley kernel easily distinguishes the barley from the rice in such mixtures.
It has been reported that barley pearling rates of 30 to 40% are optimum to retain maximum levels of soluble dietary fiber and beta-glucan (Pederson et al, World Rev. Nutr. Diet., 60:1, 1989). It is further known that varying degrees and methods of barley processing will produce fractions that vary widely in physical and chemical composition.
Barley bran (excluding the hull) consists of testa and pericarp, germ, the tricellular aleurone, and the subaleurone layers. Barley, unlike wheat and oat, is a difficult grain to roller-mill into flour. Barley bran is brittle and has a tendency to shatter regardless of tempering conditions. Further, as barley is a soft grain, barley flour tends to be sticky and may be difficult to work with. It has been determined that 25 to 30% of the outer grain coverings may approximate bran and allow flour yields of 70 to 75%.
Due in part to the favorable nutritional profile of barley, there is a desire to increase the market acceptance of barley products. Two major market opportunities are the hot breakfast cereal market and the rice replacement market. However, the largest hurdles to consumer acceptance are the lengthy soaking and cooking times required. A quick-cooking barley product with favorable nutritional profile is desirable.
Although there has been great effort in rice processing research over the last four decades, there is still active interest in developing new and improved quick-cooking rice products and alternatives. Moreover, rice processes are not directly applicable to barley, as the structure and substance of the grain differs significantly from rice.
In U.S. Pat. No. 2,890,957 and No. 2,944,904, Seltzer describes a quick-cooking process for barley or rice. Barley or rice grains are soaked in water to hydrate without gelatinizing, steamed under pressure to gelatinize, compressed and finally dried. Barley prepared in this manner appears physically deformed due to the compression step.
Alternatively, U.S. Pat. No. 3,495,989, describes a process for the preparation of barley and a wide variety of other quick-cooking foods. The process entails soaking the barley in saline solution, tempering, gelatinizing in hot air, packaging and pasteurizing. The product has higher moisture content than the unprocessed grain and requires vacuum packaging.
U.S. Pat. No. 4,707,371 describes a process for the preparation of microwavable barley by utilizing pressure-cooking as a first gelatinizing step, soaking for a period of time, and drying over a period of 90 min.
A further process is described in U.S. Pat. No. 5,464,647. A quick-cooking barley product is produced by: cooking pearled barley to raise the moisture content of the barley to 55 to 65%; subjecting the barley to an atmosphere of pressure with saturated steam, while spraying hot water onto the barley in order to obtain a drained moisture of 70%-80%; draining; and drying to a moisture content of about 12% or less.